A grating coupler launches a surface plasmon on a copper film in air at a vacuum…

PHYSICS · Subjective · Fermi University Physics · Optics & Photonics · Condensed Matter, Materials & Soft Matter · Wave propagation and light in media

What an Instrument Can See, Ch Media that are designed: plasmons, metamaterials and photonic crystals

Problem

A grating coupler launches a surface plasmon on a copper film in air at a vacuum wavelength of 1550 nm1550\text{ nm}, where copper's complex relative permittivity is ϵ~m=−90+10i\tilde\epsilon_m = -90+10i against air (ϵd=1\epsilon_d = 1). The grating has period Λ=1400 nm\Lambda = 1400\text{ nm} and couples in first order (m=1m=1), so that k0sin⁡θ+m 2πΛ=Re ksp.k_0\sin\theta + m\,\frac{2\pi}{\Lambda} = \mathrm{Re}\,k_{\mathrm{sp}}. Find the magnitude of the angle of incidence θ\theta, measured from the surface normal, at which the plasmon is excited.

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